Optimise or Optimize: Which Spelling Is Correct ?

You may have seen both optimise and optimize online and wondered which one is correct. This confusion is very common, especially for writers, students, SEO experts,

and professionals who write for a global audience. Both spellings look right, both appear in trusted sources, and both are used in serious writing. So why do two versions exist?

People search for “optimise or optimize” because they want a clear answer fast. They want to know which spelling is correct, which one sounds more professional, and which one fits their audience.

This confusion often appears when writing blogs, emails, academic papers, or website content. Using the “wrong” version can feel risky, even though the meaning is the same.

This article solves that problem. You will get a quick answer, a simple explanation of where both spellings came from, and clear advice on which one you should use.

By the end, you will know exactly when to write optimise and when to write optimize, without guessing.

Optimise or Optimize – Quick Answer

Both optimise and optimize are correct.

Optimise is used in British English
Optimize is used in American English

Examples:

UK: We need to optimise the website for speed.
US: We need to optimize the website for speed.

The meaning is the same in both cases.

The Origin of Optimise or Optimize

The word comes from the Greek word “optimos,” meaning best. It entered English through Latin and French.

The spelling difference happened later:

British English preferred -ise
American English preferred -ize

Both forms are historically correct. The difference is about spelling rules, not meaning or quality.

British English vs American English Spelling

British and American English follow different spelling systems.

Key difference:

British English: -ise
American English: -ize

Examples:

Optimise (UK) / Optimize (US)
Organise / Organize
Realise / Realize

Comparison Table

British English	American English
optimise	optimize
organise	organize
realise	realize

Which Spelling Should You Use?

It depends on your audience.

US audience → Use optimize
UK audience → Use optimise
Australia, Canada, NZ → Usually optimise
Global or SEO content → optimize is more common online

Tip: Pick one spelling and stay consistent.

Common Mistakes with Optimise or Optimize

Here are common errors to avoid:

❌ Mixing both spellings in one article
✅ Choose one style and stick to it
❌ Thinking one is wrong
✅ Both are correct
❌ Using British spelling for US clients
✅ Match your audience

Optimise or Optimize in Everyday Examples

Emails

UK: Let’s optimise our workflow.
US: Let’s optimize our workflow.

News

The company plans to optimize costs.

Social Media

Tips to optimize your Instagram bio.

Formal Writing

The system was optimised for efficiency.

Optimise or Optimize – Google Trends & Usage Data

Search data shows:

Optimize is more popular worldwide
Optimise is common in the UK and Commonwealth countries

In SEO and tech content, optimize appears more often because most tools and platforms follow American English.

Comparison Table: Optimise vs Optimize

Feature	Optimise	Optimize
Meaning	Same	Same
English Type	British	American
SEO Usage	Lower	Higher
Correct?	Yes	Yes

FAQs: Optimise or Optimize

1. Is optimise British English?
Yes, it is standard in British English.

2. Is optimize American English?
Yes, it follows American spelling rules.

3. Do they mean the same thing?
Yes, the meaning is exactly the same.

4. Which is better for SEO?
Optimize is searched more globally.

5. Can I use both in one article?
No, it looks unprofessional.

6. Which should students use?
Follow your school’s English style.

7. Is optimise wrong in the US?
It is not wrong, just uncommon.

Conclusion

The choice between optimise and optimize is not about right or wrong. Both spellings are correct and accepted in modern English. The real difference comes from who you are writing for.

British English prefers optimise, while American English uses optimize. The meaning never changes.

If your audience is in the UK or Commonwealth countries, optimise feels natural and correct. If your audience is in the US or global online markets, optimize is usually the better choice. This is especially true for SEO, technology, and digital content.

The most important rule is consistency. Choose one spelling and use it everywhere in your content. This makes your writing clear, professional, and easy to trust.

Once you know your audience, the decision becomes simple. You are now fully confident in when to use optimise or optimize.